There has been a long felt need for improved patient care apparatus in the form of a convalescent bed which helps alleviate various physical and medical problems associated with persons who are confined to a bed for extended periods of time. The difficulties and secondary trauma resulting from such confinement are well documented. Many problems arise when a person's body is in a prone position and is un-moved for extended periods of time. For example, restricted movement of the body can cause blood to pool in lower portions; this pooling of blood can cause life threatening clots. Another significant secondary effect of such restricted movement is that the patient is subjected to a higher risk of pneumonia induced by stagnation of the bodily fluids. Other side effects, while less life threatening, are nonetheless unpleasant at best but potentially quite painful; these side effects include pressure sores (decubiti), other bed sores and kidney stones. Finally, it is not uncommon for persons who have prolonged periods of restricted movement to experience atrophied muscles.
In recognition of these problems, medical personal have long known that, when caring for bed ridden patients, it is necessary to turn the body of the patient periodically so that the weight thereof rests on different longitudinal sectors such as the right side, the left side and the back. The manual turning of a patient is, to say the least, cumbersome since often the patient may not be able to assist the turning operation, in any manner. In a hospital context, the to turn various patients can consume an inordinate amount of nursing care time and, where other emergencies often arise, the turning of a patient can often be delayed or overlooked. In a home care setting, the need to turn the convalescing person or patient from side to side requires almost the continuous presence of care personal which can place increased time pressures on family and friends or significant financial costs for in home medical care.
While there has been some development of mechanical apparatus to facilitate the manual turning of a patient in order to make this process less physically demanding or cumbersome on nursing personal, these turning apparatus commonly comprise articulated beds which have folding panels or sections. Of more interest to the scope of the present invention, however, are those bed constructions which pivot or oscillate about a longitudinal axis so as to shift the convalescing persons weight back and forth between his/her sides.
To this end, it may be helpful to recognize that the concept of a rocking bed, per se, was recognized many years ago in the form of rocking cradles for infants. These devices, however, were directed to mental calming an infant or a child for rest and inducement to sleep; these devices were not developed for purposes of eliminating potential physical trauma to a bed-ridden patient. Such mechanized cradle rocking structures have been taught at least as early as those devices such is shown in U.S. Pat. No. 459,555, issued 15 Sept. 1891, to Sutton and in U.S. Pat. No. 1,334,042 issued 16 Mar. 1920 to Lopatka. The patent to Sutton discloses a spring motor which oscillates a cradle bed along rockers which are supported on a main support frame to provide oscillatory movement for a child placed therein. The Lopatka patent discloses a hemispherical cradle which is spring driven for oscillatory motion to a main frame. In both of these disclosures, however, the structure provided is directed to a temporary rocking motion directed to relaxing a small child placed in the cradle as opposed to eliminating physical trauma as described above.
More germane to the scope of the present invention, though, are those rocking bed structures adapted to adjust the position of a patients body on the bed so as to shift the weight of the convalescing person to different portions of the body. One such example of a tilting bed is described in U.S. Pat. No. 3,013,281 to Steiner issued 19 Dec. 1961. In this patent, a cradle frame provides a rigid mattress support surface which is trough shaped in configuration. The cradle frame may reciprocally pivot about a longitudinal pivot axis. A gear is rigidly affixed to the axle of the cradle frame, and a hand crank drives a worm gear which drives the axle gear thus allowing a care person to manually rock the cradle frame from side to side and thereby shift the weight of the person supported thereon.
Another example of a prior art device is described in U.S. Pat. No. 3,737,924 issued 12 June 1973 to Davis. Here, a hemispherical cradle frame is pivotally journaled to a main frame by oppositely extending trunnions. A rocker arm assembly is interconnected to the cradle frame so that an electrical motor may drive a continuous chain that operates the rocker arm so as to oscillate the cradle frame between opposite angular orientations.
A further example of a prior art device showing an oscillatory patient bed is described in Australian Patent No. 210,469, lodged 5 Oct. 1955, by Cullis. In this Australian patent, a trough shaped bed supports a mattress as a lower flattened section longitudinally extending between a pair of upwardly extending side mattress sections on a wire under mattress. A reversible motor and drive chain assemblies provided, a limit switches are mounted on the underside of the trough shaped cradle to contact limit switches to reverse the direction of rotation of the cradle frame. In this manner, the cradle frame periodically cycles in a forward and reverse direction whereby the body of an invalid placed thereon will be rocked between his/her left and right sides.
Other examples of beds which may be rocked and locked into a desired angle of rotation are shown in U.S. Pat. No. 3,875,598 issued 8 Apr. 1975 to Foster et al and in German Patent No. 2,636,746 issued 30 Mar. 1978 to Malenski. In the Foster et al device, a cradle assembly is freely rotatable about a longitudinal axis, but a brake assembly is provided to lock the cradle against rotation and at a desired orientation. In the patent to Maleski, a trough shaped bed may be pivoted in an oscillatory manner by a motor which drives a worm gear which moves a geared carriage interconnecting the worm gear and the apex of the trough shaped cradle.
Despite the advances made by these various structures, there remains a need for improved bed structures which help eliminate the dangers and difficulties attendant persons who are confined to beds over extended periods of time and who are subjects of restricted movement.